By virtue of high pressure, it is possible to print fluids having a particularly high viscosity such as, for instance, viscous fluids having a viscosity of 500.10-3 Pa·s when being processed. Possible new substances are, for instance, viscous polymers such as UV-curing polymers which may or may not be provided with fillers such as ceramic and particular pigments. With the apparatus according to the invention, such viscous substances can be used for, for instance, printing three-dimensional objects according to a rapid prototyping approach. Also light-emitting polymers and dispersions (water with particles therein; slurries, etc.) can be printed continuously with such an embodiment. It is now also possible for dispersions with a filling degree of 10-40 weight percent to be printed continuously. Other applications may include providing a droplet forming stream of fluid.
The high pressure printing system is sensitive for stable drop forming, in order to provide in a predictable manner droplets to be administered with respect to predetermined timing and placement positions. Conventionally, the printing head has a sensitivity with respect to varying printing pressures, which may be caused by the pressurizing system for providing the printing pressure. It has been found that conventional pressure systems provide unacceptable variations of printing pressures, in particular, piston driven pressure systems. In addition, a variation of the viscosity of the printing fluid may also cause drop variations that are disadvantageous.